The medicinal fungus Phellinus Igniarius (P. igniarius) has been demonstrated to possess a variety of pharmacological effects, including anti-oxidant, anti-tumor, blood circulation promotion, anti-diarrheal and sedative properties, etc. In order to gain a deeper understanding of the components in P. igniarius extract and its dynamic process in vivo, an ultra-performance liquid chromatography-triple quadrupole mass spectrometry method was developed and validated for the simultaneous determination of 12 major components (nobiletin tangeretin, narirutin, 3,4-dihydroxybenzaldehyde, hesperidin, hispidin, caffeic acid, hispolon, osmundacetone, amygdalin, salvianolic acid B and protocatechuic acid) of P. igniarius extract in rat plasma. The analyses were conducted using an ACQUITY UPLC BEH C18 column with acetonitrile and 0.1 % formic acid (v/v) in aqueous solution as the mobile phases. The intra-day and inter-day precision was less than 12.61 % for all 12 experiments, with a precision range of -11.28-12.25 %. Extraction recovery exhibited a range of 74.03-114.33 %, while the matrix effect demonstrated a range of 83.95-119.28 %. The stability tests demonstrated that the analytes remained stable, with relative standard deviations below 11.65 %. The pharmacokinetic parameters of the 12 compounds in rat plasma after oral administration of P. igniarius extract were successfully determined by the established UPLC-MS/MS method. The findings presented a pivotal foundation for advancing future research on the in vivo processes and mechanisms underlying the effects of P. igniarius extracts.